Conventional carbide button rock bits are characterized by a cutter carrying generally in the form of a sleeve like-body adapted to be mounted on a drill rod the interior bore of which terminates at a head portion of high hardness and usually embodying coolant ducts or passages leading from the inner bore to exterior surfaces at the sides of the bit and in addition sometimes at the exterior central axis of the bit. So-called carbide buttons may have an exterior hemispherical shape or other shape and embody a mounting shank portion adapted to seat in a bore formed in the drill head, the same may be retained in same bore by brazing, silver soldering or the like and in some designs of such bits the metal of the head will be deformed around the margin of the bore holding the carbide button or insert to form a retaining lip tightly gripping the insert. In spite of all efforts such as described to retain the insert firmly in assembly with the head it is a common characteristic of such drill bits that one such button or insert may work loose sufficiently at an early stage of bit use to fracture or come loose, the free portion being thereby free to effect serious damage to the remainder of the buttons on the drill bit face. Accordingly, there is a need in this class of drill bit for the firm anchorage of carbide insert buttons in the bit face of the drill head body.